Use SMTP no authorization for Office 365 in Magento 2

First of all you need to install Mageplaza Extension , you can find it here

https://github.com/mageplaza/magento-2-smtp

 

after you create O365 SMTP connector that you may use as smtp server to allow sending out emails as group

 

you need to override this class

vendor\mageplaza\module-smtp\Model\Config\Source\Authentication.php

change value of None from '' into 'smtp'.

then go to the configuration and choose None and click on Save

that's it :)